There’s a great big metaphysical joke at the core of the genius that was Henri Matisse, and it has to do with the idea of work, of labor, of effort.

Matisse, in his full-throated maturity, represents the opposite of these things. His work stands for ease and effortless beauty, and for an almost total absence of pressure – the pressure of careful outlines and fastidiously filled-in paint and, by extension, of life itself, with its repressed desires, irreconcilable demands, and emotional heavy-lifting.

In the fall of 1914, as Parisians scrambled to flee the approaching German army, Henri Matisse fled to Collioure, the fishing village in southwestern France where he had developed Fauvism, modern art’s first movement. When the Matisses arrived in the south, their first order of business was to find a tutor for their children, whose school-town of Noyon was swiftly taken by the Germans at the outset of the war. Not only did the Matisses quickly find a tutor, they found fellow Parisian exiles Juan and Josette Gris, who, as it turned out, were lodging with the tutor. The Grises were broke and desperate for both cash and companionship. Matisse quickly set about finding them both income: He arranged a system by which Gertrude Stein would help out the Grises in exchange for paintings (Stein eventually reneged on the deal), and he insisted that Josette accept a model’s fees when she sat for a series of etchings. The two families became fast friends.

In 2003, the Museum of Modern Art put on an important show comparing Pablo Picasso and Henri Matisse, maybe the two greatest European painters of the 20th century. They were friends and rivals; they influenced and even collected each other’s work.

Now a marvelous new show at MoMA — “Matisse: Radical Invention, 1913-1917” — suggests one central way Matisse was very different from Picasso. The Spanish master, practically a synonym for modern art, had an unstoppable sense of direction. He’d pursue one style — a Blue Period, a Rose Period, Cubism — and when he got to the bottom of it, he’d move on to another.

But in the four-year period this Matisse show investigates, that artist’s development emerges as much less linear, much less divided into straightforward chapters. Matisse seemed to be trying all sorts of different things at the same time, and he produced some of his greatest paintings. But it would be hard for anyone not an art historian to place the work in chronological order.